In order to understand variability in second language (L2) acquisition, this study addressed how individual differences in cognitive abilities may contribute to development for learners in different contexts. Specifically, we report the results of two short-term longitudinal studies aimed at examining the role of cognitive abilities in accounting for changes in L2 behavioral performance and neurocognitive processing for learners in "at-home" and "study-abroad" settings. Learners completed cognitive assessments of declarative, procedural, and working memory abilities. Linguistic assessments aimed at determining behavioral sensitivity and online processing of L2 Spanish syntax were administered before and after a semester of study in either a traditional university classroom context (Experiment 1) or a study-abroad context (Experiment 2). At-home learners evidenced behavioral gains, with no detected predictive role for individual differences in cognitive abilities. Study-abroad learners evidenced behavioral gains and processing changes that were partially accounted for by procedural learning ability and working memory. Taken together, these results provide preliminary insight into how individual differences in cognitive abilities may contribute to behavioral and neural processing changes over time among learners in different natural contexts.